1. Field of the Invention
This invention relates to a photographing lens device in which lenses of a 3-component lens system are retained on a lens barrel.
2. Description of the Prior Art
A specific technique for a lens system of a photographing lens device in which a plurality of lenses are assembled in a mutually contacting relationship is disclosed in Japanese Utility Model Laid-Open No. 59-58410 wherein the lenses have flat portions formed at mutually contacting zones thereof and, in assembling the lenses, the flat portions are contacted with each other in order to establish alignment of the optical axes of the lenses whereafter the lenses are adhered to each other to make a unitary lens system. In the technique, the flat portions of the lenses are provided in order to establish alignment of the optical axes of the lenses with a high degree of accuracy, and a bonding agent is used in order that the aligned lenses may not come out of the aligned condition. Thus, the flat portions of the lenses and the bonding agent are used as an optical axis aligning means for the lenses.
In a 3-component lens system including first to third lenses, conventionally such a structure for retaining the lenses on a lens barrel may be employed that the lenses are pressed from an object side outer peripheral face of the first lens with an image side outer peripheral face of the third lens contacted with a lens holding face of the lens barrel. However, where the first lens is made of a glass material and the second and third lenses are made of plastic materials, such a structure as described just above has a disadvantage that the second and/or third lenses may suffer from distortion which will deteriorate the accuracy of the shape of the second and third lenses. Besides, such a lens system which includes a plurality of lenses requires accurate alignment of the optical axes of the lenses.